Customer Concentration (Percentage of Total Revenue From Licenses Over 10% of Revenue) (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Genentech [Member] | Avastin [Member]
Revenue, Major Customer [Line Items]
Concentration Risk, Percentage	0.00%	0.00%	0.00%	22.00%
Genentech [Member] | Herceptin [Member]
Revenue, Major Customer [Line Items]
Concentration Risk, Percentage	0.00%	0.00%	0.00%	22.00%
Elan [Member] | Tysabri [Member]
Revenue, Major Customer [Line Items]
Concentration Risk, Percentage	2.00%	28.00%	13.00%	24.00%
Depomed [Member]
Revenue, Major Customer [Line Items]
Concentration Risk, Percentage	50.00%	18.00%	50.00%
Noden [Member]
Revenue, Major Customer [Line Items]
Concentration Risk, Percentage	24.00%			8.00%
Noden [Member] | Tysabri [Member]
Revenue, Major Customer [Line Items]
Concentration Risk, Percentage		26.00%	17.00%